In Germany, a bloodhound named Rex discovers a Cocker Spaniel puppy stealing secret codes before revealing itself as Kitty Galore, a hairless Sphynx cat. Rex reports this incident to D.O.G. HQ. At a car dealership in San Francisco, the mascot Crazy Carlito plans to destroy the dealership building. The police arrive, and officer Shane Larson and his police dog Diggs arrive to stop Carlito. Diggs takes the remote detonator from Carlito but bites it in the process, blowing up the building. Butch and Lou, now a fully grown Beagle and the head of D.O.G. HQ, watch Diggs blowing up the car dealership. Lou wants to recruit Diggs as an agent, and Butch reluctantly agrees.
Diggs gets locked up in the police kennels to prevent him from causing any more incidents. When Shane leaves, Butch comes in through the floor, recruits him, and takes him to D.O.G. HQ. After tracking down a pigeon named Seamus with valuable information, Diggs and Butch meet a M.E.O.W.S. (Mousers Enforcing Our World's Safety) agent named Catherine who was after Seamus for the same reason the dogs were. Catherine reveals to Diggs that Kitty Galore was a former M.E.O.W.S. agent named Ivana Clawyu who, while on a mission at a cosmetics factory, was chased by a guard dog and fell into a vat of hair removal gel, causing her to lose all her fur. Unrecognized and humiliated by her fellow agents and humans, Kitty left M.E.O.W.S. and vowed to exact revenge on humans and dogs.
Lou forms an alliance with Tab Lazenby, the head of M.E.O.W.S, to take down Kitty Galore. At a cat lady's home, the team discover that Calico, the middle-cat who was Mr. Tinkles' former aid, has been sending parts of stolen technology to Kitty using pigeons that work for her. Diggs tries to attack Calico, who then attempts to drown the team in cat litter; due to some quick thinking they eventually manage to escape. Afterwards, they interrogate Calico as to Kitty's whereabouts, but he claims that he doesn't know where she is because the pigeon couriers are flying the stolen technology to a secret location.
The group travels to Alcatraz where Mr. Tinkles is currently a mental patient. They try to get him to tell him Kitty Galore's whereabouts, but he only gives them one clue: A cat's eye reveals everything. When Kitty Galore learns about the cats and dogs working together, she hires two mercenaries named Angus and Duncan MacDougall to attempt to assassinate Seamus on the boat returning from the prison. Diggs subdues Angus and accidentally throws him overboard. Fed up with Diggs ruining the mission, Butch dismisses him from the team and leaves with Seamus to salvage clues.
Catherine takes Diggs to her home. She learns that the reason why Diggs never follows orders is because his past experiences have caused him to believe that he cannot trust anyone except himself, which led to him spending the majority of his life in kennels. She tells Diggs if he continues to think in this way, no one will able to help him. Diggs realizes how stupid he has been. Catherine takes Diggs to M.E.O.W.S. HQ, where they learn that Kitty is hiding at a fairground with her new master, an amateur magician named Chuck the Magnificent.
Not long after arriving, Diggs and Catherine are captured by Kitty Galore and her henchcat, Paws. Kitty reveals to Diggs and Catherine that she plots to transmit "The Call of the Wild" via an orbiting satellite which only dogs can hear through televisions, radios and cell phones to cause them to act hostile towards their humans. They will then be left alone and unwanted in kennels. Diggs and Catherine escape and meet up with Butch and Seamus. Kitty uses the roof of the fairground's flying swings ride for a satellite dish. Diggs, Butch, Catherine and Seamus arrive. Seamus presses a red button, thinking it is a shutdown button, but it instead loads the "Call of the Wild" signal. Dogs around the world start acting insane in their homes. Paws battles them, revealing he is a robot in the process. Diggs tricks Paws into biting the wires, destroying the satellite. Kitty's pet mouse, Scrumptious, fed up with Kitty's abuse towards him, fires her away. Kitty gets covered in cotton candy and lands in the magician's hat with the humans thinking it was a stunt.
After the mission, Diggs goes to live with Shane before returning to H.Q. to learn that Mr. Tinkles has escaped from prison with Calico.
John Whitesell was attached to direct this film, but Brad Peyton replaced him as director.
Cats & Dogs: The Revenge of Kitty Galore earned $4,225,000 on opening day, and $12,279,363 on its opening weekend reaching #5 at the box office and having a $3,314 average from a very wide 3,705 theaters. In its second weekend, its drop was very similar to the first movie, retreating 44% to $6,902,116 to 7th place and lifting its total to $26,428,266 in 2 weeks. It held better in its third weekend, dropping 39% to $4,190,426 and remaining in the Top 10. The film closed on October 21, 2010 after 84 days of release, earning $43,585,753 domestically. Produced on an $85 million budget, the movie is considered a huge box office bomb, as it grossed less than half of the first Cats & Dogs, but it did manage to do better business than fellow summer talking animal competition Marmaduke. It earned an additional $69 million overseas for a worldwide total of $112.5 million. During its initial American theatre release, the film was preceded by the new 3D animated short film titled Coyote Falls with Wile E. Coyote and Road Runner.
Rotten Tomatoes, a review aggregator, reports that 14% of 96 surveyed critics gave the film a positive review; the average rating is 3.6/10. The site's critical consensus reads, "Dull and unfunny, this inexplicable sequel offers little more than the spectacle of digitally rendered talking animals with celebrity voices." On Metacritic, the film has a score of 30 out of 100 based on 22 critics, indicating "generally unfavorable reviews". Audiences polled by CinemaScore gave the film an average grade of "B-" on an A+ to F scale.
Joe Leydon of Variety wrote a positive-leaning review towards the film which reads "Nine years after Cats & Dogs fetched more than $200 million worldwide with its comic take on interspecies animosity, Warners is unleashing Cats & Dogs: The Revenge of Kitty Galore, a faster, funnier follow-up in which CGI-enhanced canines and felines effect a temporary truce to combat a common enemy." Critics cited the plot as recycled. Scott Tobias of The A.V. Club negatively reviewed the film's plot saying "it’s still about a feline plot for world domination, and the slobbering secret agents who stand in the way." The film was nominated for a Golden Raspberry Award for "Worst Eye-Gouging Misuse of 3D", but it lost to The Last Airbender.
A video game was developed by 505 Games and it was released on July 20, 2010 for the Nintendo DS. It is called Cats and Dogs: The Revenge of Kitty Galore after the movie with the same name.
The DVD, Blu-ray, and 3D Blu-ray copies of Cats & Dogs: The Revenge of Kitty Galore were released on November 16, 2010.